1. Field of the Invention
The present invention is broadly concerned with an improved, solution phase technique for the synthesis of nitriles such as acrylonitrile and benzonitrile. More particularly, it is concerned with nitrile syntheses wherein a transition metal complex bearing an imido moiety (R--CH.sub.2 --N.tbd.) is reacted in solution under time and temperature conditions to form a nitrile (R--C.tbd.N) corresponding to the imido moiety.
2. Description of the Prior Art
Current worldwide production of acrylonitrile is approximately 8 billion pounds per year, virtually all of which is polymerized to form polyacrylonitrile used in fabrics, fibers, containers and elastomers. Virtually all commercial acrylonitrile is produced by high temperature, energy-intensive heterogeneous catalysis methods wherein a mixture of hot gases (propylene, ammonia and oxygen) are passed over a metal oxide surface in an extremely exothermic reaction. Such heterogeneous systems are notoriously complex, contain a multitude of different possible active sites, and cannot be analyzed in detail. Moreover, the overall yield of acrylonitrile (based on propylene) is in the range of 65-85%, an inefficiency that is dramatic for such large scale processes. Finally, current industrial techniques produce environmentally noxious acetonitrile and hydrogen cyanide as byproducts.
In Maatta et al. Am. Chem. Soc., 110:8249 (1988), the complex [CH.sub.2 .dbd.CH--CH.sub.2 --N.dbd.WCl.sub.4 (THF)]was reacted only with a stoichiometric amount of a specifically chosen base (butyl lithium) in order to characterize an intermediate species. This stoichiometry prevented the formation of acrylonitrile.
Accordingly, a relatively low temperature, solution phase process free of detrimental byproducts for the production of nitriles would be a decided breakthrough in the art.